FIELD OF THE INVENTION
The present invention relates to a scouring pad. More particularly, the invention relates to a scouring pad composed of a steel wool-like mat made of fine metal threads and a detergent adhered thereto.
Stains on cooking pots and pans caused by overflowing, scorching and cooking of foods, stains on stoves and ovens, grease stains on ventilation fans and stains on tile joints are commonly observed in homes. They are conspicuous, undesirable and difficult to remove. Detergents comprising an alkali and a solvent, ammonia and caustic alkalis, brasive cleansers, pot cleaners and brushes composed of steel wool, nylon and metals, spatulas, knives and the like have heretofore been used for removing these stains. The chemical actions of detergents and the like are quite effective for removing stains formed by modification or polymerization of oils caused by heat, light or air, but they are not very effective for removing stains formed by scorching and carbonizing of overflowed soups, oils and the like. The physical actions of mechanical polishing materials such as polishing cleaners and brushes composed of nylon, steel wool and metals not only remove the stains but also abrade the underlying surface. Therefore, the surface of the pot, pan, tile or plastic article is damaged and scratched by the stain-removing operation. Accordingly, the appearance of the cleaned surface is degraded to a matte finish and the cleaned surface can easily be contaminated with stains again. In the case of a soap-filled steel wool pad or cleaner, the amount of scratching is reduced as compared with the results obtained using a soap-free brush or cleaner, but the scratch-preventing effect is still insufficient.
We have discovered a scouring pad capable of achieving the following objects:
(1) The scouring pad has a high washing power such that it can remove effectively oil stains, scorching stains, roasting stains and the like; PA1 (2) The scouring pad does not damage the underlying material such as steel plate, aluminum sheet, stainless steel sheet, tile, plastic article or the like; PA1 (3) The detergent contained in the steel wool pad is not easily removed therefrom and the scouring pad is highly durable.
We have found that the foregoing objects can be attained by employing a scouring pad comprising a spongy mat of fine metal threads and a detergent impregnated therein, wherein the detergent comprises a mixture of a salt of a phosphoric acid ester and a fatty acid soap.
The phosphoric acid ester salt that is used in the present invention has the following formula (I): EQU [R(OCH.sub.2 CH.sub.2).sub.m ].sub.x PO.sub.4 H.sub.3-x-y M.sub.y (I)
wherein R is alkyl or alkenyl having 10 to 22 carbon atoms, preferably 12 to 18 carbon atoms, or alkylphenyl having 6 to 18 carbon atoms, preferably 8 to 14 carbon atoms, in the alkyl group, wherein said alkyls and alkenyl can be linear or branched, m is from 0 to 10, preferably from 0 to 5, x is from 1.0 to 2.0, y is from 0.5 to 2.0, with the proviso that the sum of x and y does not exceed 3, and M is an alkali metal such as sodium or potassium, ammonium, alkanolamine such as monoethanolamine, diethanolamine or triethanolamine, alkaline earth metal such as calcium or magnesium, zinc or aluminum cation.
The fatty acid soap that is used in the present invention includes salts of saturated or unsaturated fatty acids having 10 to 22 carbon atoms, preferably 12 to 18 carbon atoms, with alkali metals such as sodium and potassium, ammonia, alkanolamine such as monoethanolamine, diethanolamine and triethanolamine, alkaline earth metals such as calcium and magnesium or polyvalent metals such as aluminum. From the viewpoints of best adherence to the fine metal threads and water solubility, a sodium salt of coconut fatty acid or beef-tallow fatty acid is preferably employed.
The amount of the phosphoric acid ester salt in the detergent composition is from 2 to 50% by weight, preferably 5 to 40% by weight, especially preferably 10 to 30% by weight, and the amount of the fatty acid soap is from 40 to 98% by weight, preferably 50 to 95% by weight, especially preferably 60 to 85% by weight.
The weight ratio of the detergent composition to the metal thread mat is from 0.2/1 to 2.0/1, preferably 0.5/1 to 1.5/1.
The detergent can optionally contain other water-soluble surface active agents and water-soluble inorganic salts in addition to the above-mentioned phosphoric acid ester salt and fatty acid soap.
As the optional surface active agents, there can be used anionic surface active agents, nonionic surface active agents and amphoteric surface active agents. As the anionic surface active agent, there can be mentioned, for example, alkyl sulfate salts having 10 to 22 carbon atoms, alkylbenzenesulfonate salts having 8 to 16 carbon atoms in the alkyl group, polyoxyethylene alkyl ether sulfate salts having 10 to 20 carbon atoms in the alkyl group and in which the molar number of added ethylene oxide units is from 1 to 10, polyoxyethylene alkylphenyl sulfate salts having 8 to 12 carbon atoms in the alkyl group and in which the mole number of added ethylene oxide units is from 1 to 10, salts of .alpha.-olefin-sulfonic acids obtained by sulfonating an .alpha.-olefin having 10 to 18 carbon atoms, and salts of alkane-sulfonic acids obtained from paraffins having 10 to 20 carbon atoms. As the nonionic surface active agents, there can be mentioned, for example, polyoxyethylene alkyl ethers formed by adding 1 to 20 moles of ethylene oxide to higher alcohols having 10 to 20 carbon atoms, polyoxyethylene alkylphenyl ethers formed by adding 1 to 20 moles of ethylene oxide to alkylphenols having an alkyl of 8 to 12 carbon atoms, glycerin esters of fatty acids having 10 to 20 carbon atoms, and fatty acid alkanolamides derived from fatty acids having 10 to 20 carbon atoms and alkanolamines such as diethanolamine and isopropanolamine. As the amphoteric surface active agent, there can be mentioned, for example, alkyl betaines, alkyl sulfobetaines, imidazole derivatives and alkyl alanines.
As the inorganic salt, there can be used, for example, sulfates such as sodium sulfate and potassium sulfate, carbonates such as sodium carbonate and potassium carbonate, silicates such as sodium metasilicate and sodium silicate No. 2, borates such as borax and sodium metaborate, and phosphates such as sodium orthophosphate, sodium tripolyphosphate and sodium pyrophosphate. Alkali metal silicates and alkali metal phosphates (especially secondary phosphates) possess an excellent rust-preventing effect, and when these salts are incorporated in amounts of from 2 to 20% by weight, especially 5 to 12% by weight, in the detergent composition, scouring pads having especially good properties can be obtained. Further, anionic surface active agents have an effect of enhancing the washing power, and when they are incorporated in amounts of up to 10% by weight, preferably 2 to 7% by weight, in the detergent compositions, stains formed by carbonization of overflowed soups or oils can be effectively removed.
In addition, colorants, perfumes, fungicides and mildew-proofing agents can be incorporated in the detergents according to need.
When the thickness of the fine metal threads is too large, the surface to be treated is readily scratched and the tactile feel of the scouring pad is bad. If the thickness is too small, the polishing power is reduced. Accordingly, it is preferred that the diameter of the fine metal threads is from 1 to 500.mu., especially 10 to 70.mu.. The cross-sectional shape of the fine metal threads that are used in the present invention is not critical, and fine metal threads having a triangular, square, circular or flat cross-section can be used in the present invention. Further, the material of which the fine metal threads are made is not critical, and any metals having a sufficient tensile strength to be formed in fine threads, such as plain carbon steel, stainless steel and brass, can be used. Plain carbon steel is especially preferred because it possesses an excellent polishing power and touch to the hand. A spongy metal thread mat having a circular, square, rectangular, oblong or elliptical shape (and having a sufficient thickness irrespective of its planar shape) can be used in the present invention.
The scouring pad of the present invention can be prepared by shaping the fine metal threads into an appropriate form, sprinkling thereon an aqueous solution of the detergent composition and heating the detergent-containing metal wire mat under pressure to dry same. Of course, the scouring pad of the present invention can be prepared according to other methods.